PART – B (16 Marks)
1. A tensile test was conducted on a mild steel bar. The following data was obtained from
(i) Diameter of the steel bar = 3 cm
(ii) Gauge length of the bar = 20cm
(iii) Load at elastic limit = 250 kN
(iv) Extension at a load of 150 kN = 0.21 mm
(v) Maximum load = 380 kN
(vi) Total extension = 60 mm
(vii) Diameter of rod at failure = 2.25 cm
(1) The Young’s modulus
(2) The stress at elastic limit
(3) The percentage of elongation
(4) The percentage decrease in area.
2. Three bars made of copper; zinc and aluminium are of equal length and have cross
section 500, 700, and 1000 sq.mm respectively. They are rigidly connected at their ends.
If this compound member is subjected to a longitudinal pull of 250 kN, estimate the
proportional of the load carried on each rod and the induced stresses. Take the value of E
for copper = 1.3×10
N/mm2, for zinc = 1×105 N/mm2 and for aluminium = 0.8×105
3. A bar 0.3m long is 50mm square in section for 120mm of its length, 25mm diameter for
80mm and of 40mm diameter for its remaining length. If the tensile force of 100kN is
applied to the bar calculate the maximum and minimum stresses produced in it, and the
total elongation. Take E = 2×105 N/mm2 and assume uniform distribution of stress over
the cross section.
4. A bar of 25mm diameter is subjected to a pull of 40kN. The measured extension on
gauge length of 200mm is 0.085mm and the change in diameter is 0.003mm.Calculate the
value of Poisson’s ratio and the three moduli.
CE6302 MECHANICS OF SOLIDS